Current automotive brake designs force a friction material against a rotating surface of the brake when the brake is applied. The friction material maintains slight contact with a rotating surface of the brake when the brake is not applied. In a current disc brake design, the brake comprises a caliper activated by hydraulic pressure reacting on a piston that moves along with the brake pad and clamps the brake pad on a brake rotor. When the piston moves, a piston seal contacting the circumference of the piston slightly deforms. When the hydraulic pressure is relieved, for example at the end of the stop, the piston and brake pad are pulled away from the rotor by the piston seal returning to its non-deformed shape (called “rollback”). Calipers are designed such that the piston seal rollback leaves the brake pad in slight contact with the rotor. If an air gap is left between the brake pad and the rotor, the driver experiences a poor brake pedal feel due to the caliper having to travel an additional distance to move the pads back into engagement with the rotor. The brake pedal will have no initial resistance and does not quickly generate a vehicle deceleration, which results in a typical driver perception of an unresponsive and soft brake pedal.
Leaving the friction material in slight contact with the rotating surface, however, reduces fuel economy because a small amount of friction is applied to the rotating surface during non-braking conditions. Further, leaving the friction material in slight contact with the rotating surface causes additional wear on both components. This wear is a significant problem if the rotating surface does not rotate true, for example if the rotor has a run-out, which leads to irregular wear on the components and can result in pulsation, vibration, judder, and the like while braking. This is a major cause of warranty brake repair.